The redox state and composition of northern Australian late Paleoproterozoic seas: why were the next billion years ‘boring’, and what has any of this to do with mineral deposits?

The redox state and composition of northern Australian late Paleoproterozoic seas: why were the next billion years ‘boring’, and what has any of this to do with mineral deposits?

The redox state and composition of northern Australian late Paleoproterozoic seas: why were the next billion years ‘boring’, and what has any of this to do with mineral deposits?

The Earth at about 1.8 Ga was, seemingly, on a path toward modernity driven by the slow and relentless rise in atmospheric oxygen that began 600 million years earlier at the time of the Great oxidation Event. Ferruginous late Archean and early Proterozoic oceans had yielded up their iron to form huge accumulations of BIF. Eukaryotes had evolved by this time and shallow oxygenated shelves should have been ideal places for diversification and radiation to more complex organisms, however, for the next billion years (‘the boring billion’) there was apparently little change in ocean chemistry and microbes continued to dominate all known ecological niches.

This project will address the fundamental question of why this should be so, by studying late Paleoproterozoic and early Mesoproterozoic sequences from northern Australia (including vent systems represented by supergiant sedex zinc deposits). It will use inorganic and organic geochemical tools, and study novel stable isotope systems to unravel the redox state and chemical composition of the oceans between 1.65 and 1.45Ga. Fieldwork will be in the classic Proterozoic sequences of the Mount Isa ‘Western Succession’ and the McArthur Basin. Lab work will be undertaken at the University of Tasmania and the University of California-Riverside.